Friction welding

ABSTRACT

The present invention consists in the apparatus for use in welding a first component and a second component together by friction welding, comprising drive means operative to generate reciprocatory movement, a component holder operative to hold said first component, linking means operative to transmit reciprocatory movement from the drive means to the component holder so that in operation said first component performs reciprocatory heat-generating movement, pressure means operative to exert pressure on the component holder so that in operation said first component also performs welding movement, the linking means being such as to accommodate that welding movement during friction welding, and the pressure means being such as to accommodate that heat-generating movement during friction welding. The pressure means preferably comprises ram means operative to apply force to a non-reciprocating head which is connected to the component holder through flexible connecting means enabling heat-generating movement of the holder to be accommodated. The connecting means may comprise one or more hinged links but preferably comprises one or more flexible elements. These flexible elements may comprise flexible rods or bars but preferably comprise flexible blades so orientated as to prevent movement of the component holder in a direction transverse to its heat-generating movement. Movement of the head in a direction parallel with the reciprocatory heat-generating movement of the component holder is preferably resisted by guide means which nevertheless permits the head with the component holder to perform welding movement. The guide means is preferably constituted by roller means preloaded to prevent backlash or rattling in use.

This application is a continuation of prior copending international PCTapplication No. PCT/GB90/00678, filed on May 2, 1990, the benefit of thefiling date which is hereby claimed under 35 U.S.C. § 120. .Iaddend.

This invention concerns friction welding. In particular the inventionconcerns friction welding of a kind which will be referred to herein asreciprocatory friction welding. In carrying out reciprocatory frictionwelding, two components that are to be welded together are broughttogether so that a face of one of the components is in abutment with aface of the other of the components. Relative reciprocatory movementbetween the components is caused to occur; as those faces are pressedtogether frictional heat is generated. When the temperature in theneighbourhood of the faces has reached a sufficiently high value, theheat-generating relative movement between the components is caused tocease and the components become welded together.

The mutually abutting faces of the components are normally planar, butthat is not essential provided that the surfaces are so shaped thatrelative reciprocatory movement can occur between them without thesurfaces parting one from the other during reciprocation.

During the generation of heat, material constituting parts of thecomponents adjacent to the abutting faces becomes soft. Because thecomponents are pressed together, some of the soft material is forcedaside with the result that the components gradually move towards eachother. That movement may continue for a short period after theheat-generating relative movement between the components has ceased.During that period the temperature falls, and any soft materialremaining between the components is either forced aside or solidifies asthe components become welded together. That gradual relative movement ofthe components towards each other will be referred to hereinafter aswelding movement, while the relative movement serving to generate heatfrictionally will be referred to hereinafter as heat-generatingmovement. It will be appreciated that welding movement occurs in adirection which is transverse to the direction or directions in whichheat-generating movement occurs.

When reciprocatory friction welding is used to weld metal componentstogether relatively large forces are usually involved. To simplify theapplication of those forces it has normally been the practice to arrangefor one of the components to perform all of the heat-generating movementand for the other component to perform all of the welding movement butthis can lead to problems which the present invention aims to overcomeor at least to reduce.

From a first aspect the present invention consists in apparatus for usein welding a first component and a second component together by frictionwelding, comprising drive means operative to generate reciprocatorymovement, a component holder operative to hold said first component,linking means operative to transmit reciprocatory movement from thedrive means to the component holder so that in operation said firstcomponent performs reciprocatory heat-generating movement, pressuremeans operative to exert pressure on the component holder so that inoperation said first component also performs welding movement thelinking means being such as to accommodate that .welding movement duringfriction welding and the pressure means being such as to accommodatethat heat-generating movement during friction welding.

Preferably the apparatus further comprises release means operativesubsequent to friction welding to release the component holder from thedrive means to enable the component holder to be withdrawn from thewelded components.

The linking means may incorporate at least one hinged link to enable; itduring friction welding to accommodate welding movement of the componentholder. If such a hinged link is employed, however, it is necessary forthe hinges to be pre-loaded to an extent sufficient to avoid backlashoccurring during the heat-generating movement. To avoid thatrequirement, the linking means preferably comprises at least oneflexible element which flexes to accommodate the welding movement. Thereare preferably a plurality of flexible elements; the elements maycomprise rods or bars which can flex equally readily in any transversedirection; preferably, however, the elements comprise flexible bladeswhich flex in one transverse direction but are stiff in direction atright-angles to that one transverse direction.

When the release means is provided it is preferably operative todisconnect the component holder from the drive means. The disconnectionmay take place at a location along the linking means and preferablytakes place between the component holder and a portion of the linkingmeans, such as one or more hinged links or one or more flexibleelements, that during friction welding yields to accommodate weldingmovement of the component holder.

The component holder may be such as to hold said first componentdirectly but preferably the component holder engages a fixture that inturn holds the component. By changing the fixture it is then possible toemploy the same component holder to hold, on different occasions, firstcomponents of different shapes and sizes.

The pressure means preferably comprises ram means operative to applyforce to a non-reciprocating head which is connected to the componentholder through flexible connecting means enabling heat-generatingmovement of the holder to be accommodated. The connecting means maycomprise one or more hinged links but preferably comprises one or moreflexible elements. These flexible elements may comprise flexible rods orbars but preferably comprise flexible blades so orientated as to preventmovement of the component holder in a direction transverse to itsheat-generating movement. Movement of the head in a direction parallelwith the reciprocatory heat-generating movement of the component holderis preferably resisted by guide means which nevertheless permits thehead with the component holder to perform welding movement. The guidemeans is preferably constituted by roller means preloaded to preventbacklash or rattling in use.

From a second aspect the present invention consists in first and secondcomponents welded together by means of apparatus in accordance with thefirst aspect of the present invention.

From a third aspect the present invention consists in a method offriction welding in which a first component is welded to a secondcomponent by reciprocatory friction welding at a welding, station, thefirst component performing both the necessary reciprocatoryheat-generating movement and the necessary welding movement, the secondcomponent with the first component welded to it being moved bodily and athird component being welded to the second component by reciprocatoryfriction welding at said welding station, the third component performingboth the necessary heat-generating movement and the necessary weldingmovement.

Additional components may be successively friction welded to the secondcomponent in the same manner, the second component being moved bodilywith those components already welded to it before the next component iswelded to it at said welding station.

The friction welding is preferably carried out with the aid of apparatusin accordance with the first aspect of the present invention.

The bodily movement of the second component preferably comprisesrotational movement of the second component.

From a fourth aspect the present invention consists in components weldedtogether by a method in accordance with the third aspect of the presentinvention.

Embodiments of the present invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 is a somewhat diagrammatic side view of part of a first frictionwelding apparatus embodying the first aspect of the present invention,

FIG. 2 is a somewhat diagrammatic side view to a smaller scale of thewhole of the friction welding apparatus of which a part is shown in FIG.1,

FIG. 3 is a somewhat diagrammatic end view of the apparatus, as viewedfrom the right of FIG. 2,

FIG. 4 is a schematic plan view of a device for incorporation in theapparatus shown in FIGS. 1 to 3,

FIG. 5 is a simplified side view of an inner part of a turbine bladebeing welded to a rotor,

FIG. 6 is a side view, to a smaller scale of an alternative form ofcarrier that can be used in place of a carrier shown in FIG. 2,

FIG. 7 is a side view of second friction welding apparatus in accordancewith the invention, certain parts being sectioned for clarity,

FIG. 8 is a front view of the apparatus of FIG. 7, and

FIG. 9 is a plan view of the apparatus of FIG. 7.

The apparatus illustrated in FIGS. 1 to 6 is designed for use inreciprocatory friction welding. The apparatus includes drive means 1which is operative to cause reciprocation of an output member 2 in ahorizontal direction. The drive means may comprise apparatus of the kinddescribed and illustrated in the specification of British patent No. 2199 783 of Allwood, Searle & Timney (Holdings) Limited. The axis of therotary drive member of the apparatus is indicated at 3. Linking means 4is firmly secured to a projecting end of the output member and comprisesa metal bar of which a central part is machined away to leave a pair offlexible metal blades 5. A coupling socket 6 is firmly secured to theother end of the linking means 4 and is formed with an upwardly openinglocating groove having inclined side walls. A coupling head 7 enters thegroove from above and has inclined side walls which abut those of thelocating groove. The coupling head 7 is releasably secured in thecoupling socket by cap screws 8. The coupling head is integrallyconnected to a horizontally extending bar 9 which is in turn integrallyconnected with a component holder 10. A downwardly opening channel withvertically extending side walls is formed in the component holder 10 andhouses a fixture 11 which locates a first one of the components to bewelded together. No such component is shown in FIG. 1 but in FIG. 2there is indicated the outline of a turbine blade 12 which constitutesthe first component.

A pair of flexible metal blades 13 are firmly secured to the top of thecomponent holder 10 and extend upwards to the underside of a head 14 towhich they are also firmly secured. An hydraulic ram 15 is mountedvertically above the head and acts between the head and a fixed part 16of the apparatus. The head is secured to an upper end part of avertically extending guide bar 17 which is located between heavilyloaded rollers 18 so disposed that it can move only in a verticaldirection. A nut-runner 19 is mounted on the guide bar 16 andincorporates power-driven heads of polygonal cross-section which projectfrom its underside and can engage the cap screws 8 to rotate them ineither rotational direction. The nut-runner is mounted for verticalmovement on the guide bar so that it can be moved between ah upper,disengaged position in which it is separated from the cap screws and alower, engaged position in which it engages the cap screws. Suitablepower-driven means is provided to shift the nut-runner to and fro alongthe guide bar between those positions as required.

The operation of that part of the apparatus shown in both of FIGS. 1 and2 will now be described. At the start of the operation the drive meansis inoperative to reciprocate the output member 2 and that output memberis in a central position, that is in a position half way between thelimits of its horizontal travel. The nut-runner 19 is lowered to itsengaged position and is operated to unscrew the cap screws 8 so that thecoupling head is no longer secured to the coupling socket. The ram 15 isthen operated to raise the head 14, the blades 13 and the componentholder 10 with the bar 9 and coupling head 7. A first component to bewelded, such as a turbine blade, is mounted in a fixture 11 which issecured in the component holder 10. A second component, such as aturbine disc, to which the first component is to be welded, is locatedbeneath the fixture, the second component having a planar surface lyingon a horizontal centre plane of the output member 2, a plane indicatedby the line 20. The ram 15 is operated to lower the head 14, blades 13and component holder 10 until a planar, horizontal undersurface of thefirst component abuts the complementary planar surface of the secondcomponent in the plane 20, central portions of the abutting surfacesbeing traversed by the axis 21 of the ram 15. The arrangement is suchthat when this occurs the component holder 10 is disposed at a level alittle higher than that illustrated, for example a few millimetreshigher. The nut-runner 19 is lowered to its engaged position andoperated to secure the coupling head 7 into the coupling socket 6. Asthe cap screws are tightened the blades 5 flex slightly. The nut-runneris then returned to its disengaged position.

The drive means 1 is caused to reciprocate the output member 2horizontally, while the ram 15 is caused to exert a welding force whichis transmitted to the first component. Reciprocation of the outputmember is transmitted to the first component by way of the couplingsocket 6 and coupling head 7. Owing to the inclination of the side wallsof the socket and head, the head is wedged tightly in the socket and anytendency there might otherwise be for the head to rattle in the socketis thereby avoided. As the component holder 10 reciprocates, the blades13 flex. To avoid any tendency to fretting corrosion between the blades13 and either the component holder 10 or the head 14 the blades arepreferably secured to those parts in a manner such as that described inthe specification of the aforementioned British patent No. 2 199 783with reference to FIG. 8 thereof. The frictional resistance to thereciprocatory movement between the components to be welded together maywell be considerable so that the output member may well have to exert aforce of many tonnes, for example between fifteen and one hundredtonnes. Flexure of the blades 13 causes those blades to transmit to thehead 14 horizontal reciprocatory forces but the magnitude of thoseforces is determined not by the frictional resistance between the firstand second components but by the stiffness of the blades and the extentto which they are flexed. Reciprocation of the head 14, and of the guidebar 17 to which it is attached, is resisted by the rollers 18 which areloaded so as to bear on the guide bar with sufficient force to preventany backlash or rattle occurring.

As the first component reciprocates relatively to the second component(which remains stationary) frictional heat is generated with the resultthat metal adjacent to the mutually abutting surfaces softens.Consequently some of that heated metal is expelled from between thecomponents. At an appropriate moment the drive means is caused to ceasereciprocation of the output member 2, the first component thus returningto a central position, half way between the limits of its formerreciprocatory movement. Welding force continues to be exerted by the ram15 while the components become welded together. The arrangement ispreferably such that when welding has been completed the componentholder 10 has moved downwards to substantially the position illustratedin which the blades 5 are no longer deflected. Consequently the finalposition of the first component is unaffected by any flexure of theblades 5.

The cycle of operation is then repeated, with the difference that whenthe component holder 10 is raised the first component necessarilyremains unmoved, having been welded to the second component. It is alsolikely that the design of the fixture 11 will be such that it tooremains with the first component. The vertical side walls of the fixtureenable the component holder 10 to be raised from it. When the componenthas been raised clear of the fixture 11, the fixture is withdrawn fromthe first component and the second component is moved so as to bringanother part of it to the welding station (that is a location centeredon the point 22 where the axis 21 crosses the plane 20), or to enable adifferent second component to replace the initial one. A thirdcomponent, similar to the first component is mounted in the fixture 11,or in a replacement fixture, and that fixture is mounted in thecomponent head. The ram is operated to lower the third component ontothe second component and welding then proceeds as described above.

The apparatus so far described preferably includes additional locatingmeans that is not illustrated. That locating means serves to locate thecomponent holder 10 against movement in any direction parallel with theplane 20 and traverse to the direction of reciprocation. The locatingmeans conveniently comprises two pairs of flexible blades (not shown)each similar to the flexible blades 13. Inner ends of the blades arefirmly secured to the component holder 10 as close as possible to theplane 20 though necessarily above that plane. The blades extendhorizontally outwards from the component holder 10, and outer ends ofthe blades are firmly secured to spaced, vertical walls (not shown) sideedges of which are anchored to the guide bar 17. The method ofsecurement of the additional blades is preferably similar in eachinstance to that used for securing the blades 13 to the component holder10 and the head 14. The blades of the additional locating means are soorientated that they can flex in a horizontal direction to permit thereciprocatory movement of the component holder during welding. Whenreciprocatory movement of the component holder occurs, the blades of theadditional locating means flex. Consequently the overall length of eachblade, as measured between the parallel planes of the end faces thereof,is very slightly reduced. As the maximum distance travelled by thecomponent holder from its central position during reciprocatory movementis likely to be no more than a few millimetres, the consequent reductionin the overall length of the blades is immaterial; it may for example beapproximately 0.02 mm. To accommodate that reduction the blades maystretch very slightly and/or the vertical walls may be drawn veryslightly closer together. It will be appreciated that during welding,flexure of those additional blades causes reciprocatory forces to beapplied to the guide bar 17 similar to those applied by the blades 13.The rollers 18 are sufficiently heavily loaded, however, to preventbacklash or rattle of the guide bar. It will also be appreciated thatwhen the ram 15 is operated to raise or lower the component holder, theguide rod moves up or down in unison with the head so that the verticalwalls also move up and down; the additional blades extending between thecomponent holder and the walls therefore move up and down in unison withthe head. The additional blades could alternatively be mounted onrollers similar to rollers 18 so as to be slidable up and down with thecomponent holder.

The apparatus described above, whether or not it includes additionallocating means of the kind described in the last preceding paragraph,may also include balancing means As described and illustrated in thespecification of the aforementioned British patent No. 2 199 783, thedrive means itself incorporates its own balancing means. If desired,that balancing means may be modified to balance some or all of the partsof the apparatus described above and that reciprocate when the outputmember 2 reciprocates. For example, the balancing means of the drivemeans may also serve to balance the linking means 4 and the couplingsocket 6. Alternatively, or in addition, supplementary balancing means(not shown) may be provided to balance some or all of the reciprocatoryparts described above and otherwise not provided with balancing means.The supplementary balancing means may, for example, serve to balance thelinking means 4 and all the parts which in use are reciprocated by itand illustrated in FIG. 1. Alternatively the balancing means may, forexample, merely serve to balance the coupling head 7 and all the partswhich in use are reciprocated by it.

The supplementary balancing means preferably comprises counterweightmeans which is coupled to the reciprocating parts in such a manner thatin whatever direction those parts are moving at any particular momentthe counterweight means is moving in the opposite direction. To this endthe counterweight means preferably comprises one or more counterweightscoupled to the component holder 10, or some adjacent part, by a link orlinks pivoted at an intermediate location. The pivot is preferablyattached directly or indirectly to the guide bar 17, the arrangementbeing such that in use, when the ram 15 is operated the counterweightmeans moves upwards or downwards, as the case may be, in unison with theguide bar, the head 14 and the component holder 10.

Counterweight means of this general kind has been provided not only inthe drive means that is the subject of the aforementioned British patentNo. 2 199 783 but also in other friction welding apparatus such as thatwhich is the subject of British patent No. 1 414 454 of Allwood, Searle& Timney Limited; there, counterweights 46 are provided with links orbars 47 pivoted at their centres to fixed plates 48. Thosecounterweights are also provided with flexible and resilient elements 49which exert restoring forces on the counterweights. Similar resilientelements may optionally be employed with the counterweights for use withthe present apparatus.

It will be understood from the foregoing that while frictional heat isbeing generated and welding is being effected the second componentremains stationary. Before further welding can take place at the weldingstation, however, the second component must be shifted so that the firstcomponent already welded to the second component is moved away from thewelding station. FIG. 2 illustrates support means suitable forsupporting the second component. The support means is illustrated assupporting a second component 24 constituting a rotor to which turbineblades 12 are to be friction welded. The rotor 24 has an axis 23; itsouter surface is of generally conical shape but is formed with aplurality of slightly raised portions each of which is machined toafford a planar surface to which an associated blade can be welded. Aset of those planar surfaces is arranged in a circle around the rotor,the surfaces being uniformly spaced apart around the rotor. There may beseveral sets of such planar surfaces each set being at a different axiallocation along the rotor.

As explained above, the mutually abutting faces of the first and secondcomponents at the welding station are horizontal. In order to bring eachin turn of the planar surfaces on the rotor 24 into the horizontal plane20 at the welding station it is necessary for the rotor to be rotatedabout its axis 23 while that axis is inclined at a predetermined angleto the horizontal. In the apparatus illustrated in FIG. 2 the rotor ismounted with its axis inclined to an appropriate angle. The rotor issupported between bearings 25 and 26 constituting part of a C-shapedcarrier 27 and can be rotated about its own axis 23 in those bearings.Rotation of the rotor about that axis is effected by anumerically-controlled drive, and means are provided to lock the rotorin any desired position of adjustment.

When the apparatus is in use, turbine blades 12 are sequentially weldedto a rotor so that a ring of uniformly spaced blades is secured to therotor. During this sequential welding process, after each blade (exceptthe last) has been welded in place and the component holder 10 has beenraised, the rotor is rotated about its axis 23 through the anglenecessary to bring the next planar surface on the rotor to the weldingstation.

During the frictional generation of heat, reciprocatory forces ofconsiderable magnitude are transmitted from the turbine blade to therotor. To assist in preventing consequential reciprocatory movement ofthe rotor, the carrier 27 is tied back to the drive means 1 by means ofa horizontal component 28. It will also be appreciated that owing to thedownward welding force exerted by the ram 15, a corresponding reactionforce is exerted on the fixed part 16 of the apparatus. To withstandthat reaction force the fixed part 16 is therefore preferablyconstitutes a transverse component of a bridge-like structure havingspaced parallel uprights 29, one on either side of the welding station.The lower ends of the uprights are secured to a base 30 on which theapparatus is mounted.

The downward force exerted by the ram 15 is transmitted by the firstcomponent to the rotor 24 and thence through the carrier 27 to the base30. It would be possible for the carrier to be mounted directly on thebase, but in a preferred arrangement, such as that illustrated, thecarrier is mounted in such a manner that its position can be varied soas to enable the apparatus to be used to friction-weld other sets ofturbine blades to the rotor and to enable apparatus to be used withrotors of different designs.

The carrier 27 is mounted on a support for rotational adjustment about ahorizontal axis 31 which is normal to a vertical plane containing thecommon axis of the bearings 25 and 26. To this end the carrier isprovided with trunnions which enter horizontally aligned bearings in apair of spaced, vertical walls 32 constituting part of the support. Thewalls 32, which are tapered upwards, as illustrated are fixed to a plate33 which also constitutes part of the support and which is in turnmounted on a bearer 34. The supporting plate 33 is rotatable about avertical axis 35 relative to the bearer. The bearer 34 itself can bemoved horizontally, without rotation, relative to the base, themechanism for effecting this being shown schematically in FIG. 4. Thebearer 34 is of rectangular shape in plan and is located in arectangular opening 36 in a frame 37. The length of the opening 36 isthe same as that of the bearer 34 but the width of the opening isgreater than that of the bearer. The bearer 34 can be shifted widthwiseof the frame by screw mechanism 38. Similarly the frame 36 is located ina rectangular opening 39 in the base 30. The width of the opening 39 isthe same as that of the frame 37 but the length of the opening isgreater than that of the frame. The frame, with the bearer, can beshifted lengthwise of the base by screw-mechanism 40. Rotation of thecarrier 27 about the horizontal axis 31 and the vertical axis 35 iseffected by suitable numerically-controlled motors. Similarly, operationof the screw mechanism 38 and 40 is also effected by similarnumerically-controlled motors. As the combined weight of the rotor 24,carrier 27, support 32, 33, and bearer 34 is likely to be relativelylarge, it is preferred to include means (not shown) to introducepressurised air beneath the bearer 34 and the frame 37 during operationof the screw mechanism 38 and 40 so as to reduce the frictional forcesresisting horizontal movement of the bearer and the frame. When thebearer has been shifted to any desired position of adjustment the flowor pressurised air is caused to cease and the bearer is clamped inposition by clamping means (not shown).

It will be appreciated that the support means for supporting the secondcomponent could be used independently of the particular structuredescribed for moving the first component. The support means could beused with any suitable arrangement for producing welding movement andheat generating movement of the first component.

In FIG. 5 there is shown, in simplified form, a small part of a rotor 41with a conical outer surface 42 formed with a raised portion 43, whichis one of a set of such portions spaced uniformly around the rotor. Theouter surface of the raised portion is planar and is in the shape of arectangle or a parallelogram with its length considerably greater thanits width. Part of a turbine blade 44 is also shown, this having a mainoperative portion 45 or arcuate profile in section and at its lower endflaring outwards to a base portion 46 of substantially the same shape inplan as the planar surface of the raised portion 43. Below the baseportion 46 the blade is formed with an attachment portion 47 of slightlysmaller cross-section than the base portion 46 and, like the baseportion, in the shape of a rectangle or parallelogram. When welding isto start, a planar lower surface of the attachment portion 47 is broughtinto abutment with the outer surface of the raised portion 43, thesurfaces being substantially of the same shape and dimensions. In orderto bring about the frictional generation of heat the blade isreciprocated in a direction parallel with the longitudinal axis of themutually abutting surfaces. During the frictional generation of heat azone 48 at the lower end of the attachment portion becomes soft or fluidand is squeezed laterally so that the height of the attachment portionis progressively reduced.

In some sets of raised portions, the longitudinal axis of each suchportion lies in a plane that also contains the rotational axis of therotor. When that is the case the rotor is disposed in a manner similarto that shown in FIGS. 2 and 3. In other arrangements, however, thelongitudinal axis of each such portion is inclined so as to approximateto a short length of a notional spiral or helix extending over theconical surface of the rotor. When that is the case the carrier mustfirst be rotated about the vertical axis 35 in order to bring thelongitudinal axes of the mutually abutting surfaces into alignment withthe direction of reciprocatory movement of the component holder 10.

In welding turbine blades made from a titanium alloy to a rotor for anaircraft engine, the apparatus may be such that the maximum length oftravel of the output member 2 during reciprocatory movement is about 6mm (that is the maximum length of travel from the central position isabout 3 mm); the force that can be exerted by the output member may bebetween fifteen and one hundred tonnes; the maximum force that can beexerted by the ram 15 is also between fifteen and one hundred tonnes,the force preferably being substantially equal to the force that can beexerted by the output member; in the course of the welding operationsthe turbine blade may move downwards through a distance of a fewmillimetres, for example about six millimeters. Those figures are givensolely by way of example and are in no way limiting to the scope of theinvention.

In addition to its use in the initial manufacture of bladed rotors forturbines the apparatus and method may be used in the repair of bladedrotors, broken or damaged blades being replaced by new blades which arefriction welded into place.

The apparatus may, or course, be used for welding other types ofcomponents together. In place of the carrier 27 there may be provided acarrier of the kind shown in FIG. 6. That carrier has a base plate 49 towhich a second component can be secured and spaced side arms 50 providedwith aligned trunnions for engagement in the bearings in the wall 32.

Whether using the carrier 27 or the carrier shown in FIG. 6, it may bedesirable to provide some form of load transmitting means between thecarrier and the supporting plate 33, after any necessary adjustments ofthe carrier have been effected, so that in use at least part of theforce applied to the second component by the ram 15 is transmitted, tothe supporting plate 33 and thence to the base 30 by way of that loadtransmitting means rather than by way of the trunnions and the bearingsin the walls 32. The load transmitting means may comprise a block or astack of blocks of appropriate thickness or it may comprise jack meansof adjustable height.

Moreover, in order to enable the height of the second component to beadjusted so as to enable the face of the second, component to be broughtinto the plane 20, the plate 33 may be raised or lowered relative to thebearer 34. Packing of a suitable thickness may be provided for thispurpose. In theory it might be desirable to provide a power-drivennumerically controlled screw-mechanism for adjusting the height of thesupport but as the force applied by the ram 15 would be transmittedthrough that mechanism, during welding, it may well be impracticable toprovide such mechanism in apparatus in which the ram exerts a largeforce.

It will be appreciated that any adjustment of the position of thecarrier can be carried out only after the strut 28 has been removed andthat when the carrier is in a new position of adjustment a new component28 of appropriate dimensions is required of the carrier is again to betied back to the drive means.

The supporting device described above is capable of universal adjustmentin that the second component can be rotated independently about threeaxes, 23, 31 and 35, that are transverse to each other and can be movedindependently in any of three directions of right-angles to one another,that is in horizontal directions by operation of the device shown inFIG. 4 and vertically by bodily movement of the support relative to thebearer 34. This universal adjustment is valuable in that it enables theapparatus to be used for friction welding together components of a widevariety of shapes and sizes. Nevertheless it will be appreciated thatspecial-purpose apparatus embodying the invention may be such thatfacilities for adjustment in one or more of those three rotationaland/or three translation manners are omitted.

It will also be appreciated from the foregoing that the invention stemsfrom a recognition that it is desirable for the drive means to remainfixed and for the second component to remain stationary during eachwelding operation and to be moved as little as possible betweensuccessive welding operations. The provision of release means operativebetween the component holder and the output member of the drive means,and in accordance with present invention, much assists in achievingthese aims. However, if the linking means is able to accommodate themovement of the component holder necessary to release a welded firstcomponent from the component holder and introduce a subsequent firstcomponent into the component holder then the release means may not benecessary.

It is to be understood that numerous modifications can be made withoutdeparting from the scope of the present invention. For example, adifferent form of drive means could be used in place of that describedabove. Furthermore the apparatus may be orientated differently so thatthe direction of reciprocatory movement is not horizontal; it may, forexample, be vertical in which case it may be convenient for the weldingstation to be situated above the drive means.

The apparatus illustrated in FIGS. 7 to 9 is a second friction weldingapparatus of similar general construction to the first apparatusillustrated in FIGS. 1 to 6, and similar reference numerals have beengiven to similar components but primes have been added to distinguishthem from the reference numerals of FIGS. 1 to 6. The apparatuscomprises heat-generating movement means 51, welding movement means 52,a component holder 10' coupled to the heat-generating and weldingmovement means 51 and 51 and adapted to hold a first component to bewelded to a second component, and a second component holder 53.

The heat-generating movement means 51 comprises drive means 1' which isoperative to cause horizontal reciprocation of an output member 2' whichis connected to the component holder 10' by a plurality of flexiblemetal blades 5' comprising linking means. The blades 5' are machinedfrom a single piece of metal.

The welding movement means 52 comprises a hydraulic ram 15' actingbetween a fixed part 16' of the frame and a head 14'. Flexible metalblades 13' connect the head 14' to a portion of the component holder10'.

The component holder 10' comprises a body 54 which transfers theheat-generating movement to the first component (referenced as number55), a part 56 of the body extends above the first component and servesto transfer the welding movement to the first component. The body 54 hasa vertical face 57 against which a packing block 58 is urged by a jaw 59of the component holder. The first component 55 is itself rigidlymounted in a fixture 60 clamped between the face 57 and the jaw 59 byscrews 61.

The part 56 of the body 54 has an upper surface 62 to which the blades13' are secured and a lower surface 63 which in use bears against thefixture 60.

The holder 53 for the second component is mounted on a rigid main frame64 and comprises a carriage 65 slidably mounted on a horizontal plate 66fixed to the main frame 64. The plate 66 has an array of parallelT-section slots 67 formed in its upper surface and the carriage 65 canbe releasably bolted to the plate by suitable shaped bolts 68. Avertical plate 69 with T-section slots 70 is also fixed to the mainframe 64 and the carriage 65 is releasably bolted to it by bolts 77. Thecarriage 65 comprises a main body 71 of L-shaped cross-section (bestseen in FIG. 7), having a vertical face 72, and a jaw 73 connected tothe body by screws 74 thus enabling a second component 75 to bereleasably clamped to it. The second component may be mounted in afixture similar to the fixture 60.

A reaction frame 76 is provided to transmit the reaction from thewelding force to the frame 64. The frame comprises the part 16' of theframe and four vertical tie bars 78. The upper ends of the tie bars areconnected to the part 16' and the lower ends to the main frame 64.

The head 14' is able to move vertically but is restrained from movementin horizontal directions. This restraint is achieved by two fixedvertical channels 80 fixed to the frame 64 and opening towards eachother on opposite sides of the head. Blocks 81 fixed to the head projectinto the channels. Each block carries three rollers 82 which engage theinside faces of the channels and rotate about their axes when the headmoves up and down.

The part 56 of the body 54 is able to move vertically and horizontallyin the direction necessary to cause the generation of heat; it ishowever, restrained from moving sideways. The restraint is achieved byflexible metal blades 86 which extend horizontally. Inner ends of theblades are anchored to the part 56 while outer ends thereof are anchoredto blocks 85 similar to the blocks 81. Each block 85 carries threerollers 87, like the rollers 82, which engage the inside faces of fixedvertical channels 88 similar to the channels 80. For clarity theserestraining means are not shown in FIG. 7 (apart from the blades 86which are there shown in section).

The generation of frictional heat for welding is carried out in much thesame manner as that described above with reference to FIGS. 1 to 6.FIGS. 7 to 9 show the apparatus at the moment of welding. The blade 5'are in horizontal planes and are undeflected, the output member 2'having stopped reciprocating. The ram 15' is exerting a welding force tourge the first component 55 against the second component 75.

After welding has been completed the screws 61 are released to slackenthe grip of the jaw 59 on the first component and the ram 15' isactuated to lift the component holder clear of the welded components. Asthis occurs the blades 5' flex and the head 14' and the part 56 areguided for vertical movement by the guide channels and blocks describedabove. When the portion 56 is sufficiently clear of the first componentthe bolts 68 and 77 are slackened and the carriage 65 is slidhorizontally away from its welding position to the left or right asviewed in FIG. 8. The screws 74 are then released and the weldedcomponents are either removed and replaced with a subsequent componentor re-positioned for a subsequent welding operation.

It will be appreciated that since the jaw 59 moves in such a manner asto release the first component 55 for movement in the horizontaldirection in which the carriage 65 slides, there need not be much, ifany, raising of the body 54 to allow the first component to move free ofcomponent holder 10'.

In a modified construction (not illustrated) the fixed part 16' is fixedto an upward extension of the main frame 64. The main frame 64 and fixedpart 16' are then generally C-shaped in side view. The tie bars 78, orat least some of them, may then be omitted.

I claim:
 1. Apparatus for use in welding a first component and a secondcomponent together by friction welding, comprising drive means operativeto generate reciprocatory movement, a component holder operative to holdsaid first component, linking means operative to transmit reciprocatorymovement from said drive means to said component holder so that inoperation said first component performs reciprocatory heat-generatingmovement, pressure means operative to exert pressue on said componentholder so that in operation said first component also performs weldingmovement, said pressure means being such as to accommodate theheat-generating movement during friction welding, and wherein saidlinking means comprises at least one flexible element which isalternately in compression and in tension as it transmits saidreciprocatory movement from said drive means to said component holderand which bends or flexes to accommodate the welding movement of saidcomponent holder during friction welding.
 2. Apparatus according toclaim 1 wherein release means is provided, said release means beingoperative subsequent to friction welding to release said componentholder from said drive means.
 3. Apparatus according to claim 2 whereinsaid release means is operative to disconnect said component holder fromsaid linking means.
 4. Apparatus according to claim 1 wherein saidpressure means comprises ram means operative to apply force to a headwhich is connected to said component holder through flexible connectingmeans which enables reciprocatory heat-generating movement of thecomponent holder to be accommodated.
 5. Apparatus according to claim 4wherein said component holder is restrained against movement transverseto said heat-generating movement and said welding movement by flexiblerestraining means extending between said component holder andrestraining means movable only in said direction of welding movement. 6.Apparatus for use in welding a first component and a second componenttogether by friction welding, comprising drive means operative togenerate reciprocatory movement, a component holder operative to holdsaid first component, linking means operative to transmit reciprocatorymovement from said drive means to said component holder so that inoperation said first component performs reciprocatory heat-generationmovement, pressure means operative to exert pressure on said componentholder so that in operation said first component also performs weldingmovement, said linking means being such as to accommodate said weldingmovement during friction welding, and said pressure means being such asto accommodate said heat-generating movement during friction welding,and wherein flexible restraining means is provided extending betweensaid component holder and movable restraining means, said movablerestraining means being movable only in the direction of said weldingmovement, said component holder being restrained against movementtransverse to said heat-generating movement by said flexible restrainingmeans.